diff --git a/build.gradle.kts b/build.gradle.kts
index e229a86..247cf6a 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -23,6 +23,9 @@ kotlin {
             implementation(libs.hash)
             implementation(libs.bytearray)
         }
+        commonTest.dependencies {
+            implementation(libs.test)
+        }
     }
 
     compilerOptions {
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index b02d28d..a6ad94e 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -1,7 +1,7 @@
 [versions]
 kotlin = "2.1.20"
-hash = "1.3.1"
-bytearray = "1.2.0"
+hash = "1.3.2"
+bytearray = "1.2.2"
 
 [plugins]
 multiplatform = { id = "org.jetbrains.kotlin.multiplatform", version.ref = "kotlin" }
@@ -9,3 +9,4 @@ multiplatform = { id = "org.jetbrains.kotlin.multiplatform", version.ref = "kotl
 [libraries]
 hash = { module = "com.infendro:hash", version.ref = "hash" }
 bytearray = { module = "com.infendro:bytearray", version.ref = "bytearray" }
+test = { module = "org.jetbrains.kotlin:kotlin-test", version.ref = "kotlin" }
diff --git a/src/commonMain/kotlin/com/infendro/mac/MAC.kt b/src/commonMain/kotlin/com/infendro/mac/MAC.kt
index 2f44ba2..c26424b 100644
--- a/src/commonMain/kotlin/com/infendro/mac/MAC.kt
+++ b/src/commonMain/kotlin/com/infendro/mac/MAC.kt
@@ -2,8 +2,6 @@ package com.infendro.mac
 
 abstract class MAC {
     abstract val bytes: Int
-
-    @Suppress("UNUSED")
     val bits: Int
         get() = bytes * 8
 
diff --git a/src/commonTest/kotlin/com/infendro/mac/HMAC.kt b/src/commonTest/kotlin/com/infendro/mac/HMAC.kt
new file mode 100644
index 0000000..a6f404e
--- /dev/null
+++ b/src/commonTest/kotlin/com/infendro/mac/HMAC.kt
@@ -0,0 +1,36 @@
+package com.infendro.mac
+
+import com.infendro.hash.sha2.`SHA-256`
+import kotlin.test.Test
+import kotlin.test.assertContentEquals
+import kotlin.test.assertEquals
+
+class `HMAC Test` {
+    val hmac = HMAC(`SHA-256`)
+
+    @Test
+    fun bytes() {
+        assertEquals(32, hmac.bytes)
+        assertEquals(256, hmac.bits)
+    }
+
+    @Test
+    fun `hash() - example`() {
+        assertContentEquals(
+            ubyteArrayOf(
+                0xf7U, 0xbcU, 0x83U, 0xf4U,
+                0x30U, 0x53U, 0x84U, 0x24U,
+                0xb1U, 0x32U, 0x98U, 0xe6U,
+                0xaaU, 0x6fU, 0xb1U, 0x43U,
+                0xefU, 0x4dU, 0x59U, 0xa1U,
+                0x49U, 0x46U, 0x17U, 0x59U,
+                0x97U, 0x47U, 0x9dU, 0xbcU,
+                0x2dU, 0x1aU, 0x3cU, 0xd8U,
+            ),
+            hmac.hash(
+                "key".encodeToByteArray().asUByteArray(),
+                "The quick brown fox jumps over the lazy dog".encodeToByteArray().asUByteArray()
+            )
+        )
+    }
+}